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    Life raft questions - knowing only GHA and sun's rising or setting
    From: Ed Popko
    Date: 2018 Nov 7, 08:03 -0800

    I continue to investigate the Lindbergh-Weems Hour Angle watch and it's influence on the design of subsequent navigation (aka 'pilot') watches. The growth of aviation in the 30s and 40 plus WWII celestial navigation led to some interesting designs and patents.

    It's not so surprising that most watch bloggers and collector sites don't get the usage of the Lindbergh-Weems Hour Angle watch right. they are not navigators per se. Some get the basic principles right but only a one or two get the hour angle calculation right.

    Perhaps the biggest error they make is to claim that the watch tells the pilot their longitude by direct reading missing the need for Local Hour Angle as well not to mention the correct Equation of Time or near so for the day used. Perhaps it's just wording and they mean the longitude of the sun. I don't think so.

    So the question is .. just what can you tell from a watch that accurately computes the GHA of the sun and the only other thing you now is the sun is rising or setting and is either north or south of your latitude?  Perhaps a life raft question.

    Ed


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